Some rampage or "spree" killers also want to provoke a LE response so they can go out in a "suicide by cop" event. That factor is a part of Hunter's novel; Soft Target.
LE & homeland security groups train for these incidents knowing that a violent subject(s) may be unstable or want to force a confrontation by attacking unarmed people or public places(schools, malls, movie theaters, etc).
It's a good chance that a violent subject you may encounter in a spree shooting won't really care about being arrested or even shot by SWAT/LE.